> On Thu, Nov 01, 2012 at 09:26:25PM +0100, Hans-Peter Nilsson wrote: > > > Attached patch was bootstrapped&tested on > > > > gcc/ > > PR tree-optimization/55018 > > * basic-block.h (dfs_find_deadend): New prototype. > > * cfganal.c (dfs_find_deadend): No longer static. Use bitmap > > instead of sbitmap for visited. > > (flow_dfs_compute_reverse_execute): Use dfs_find_deadend here, too. > > * dominance.c (calc_dfs_tree): If saw_unconnected, > > traverse from dfs_find_deadend of unconnected b > > instead of b directly. > > > > It seems this caused PR55168, ICE. > > As Honza said, it was likely latent, and furthermore seems to be related to > the flow_dfs_compute_reverse_execute change from Steven (mentioning it > primarily what should we consider backporting if anything to release > branches).
Indeed, this patch should not affect loop predictions. Perhaps it prevents CD-DCE from removing a loop that it previously removed and thus the loop survives till predict.c and triggers the previously latent bugs? The patch I attached to the PR is actually incorrect - estimated_stmt_executions_int already adds the +1 and thus should never return 0. I am looking into proper fix. There is obvious overflow on the other computation patch, so my best guess is that fixing it will cure the issue. Honza > > Jakub
